Leno spent four seasons with the Gunners, going on to make 125 appearances and keeping 37 clean sheets before losing his starting spot to Aaron Ramsdale in the 2021/2022 campaign.
Leno joined Fulham at the start of this season and has been an ever-present for Marco Silva's side, who find themselves seventh on the table.
Following his Arsenal exit, Leno alleged 'politics' within the club led to his departure, comments which surprised Mikel Arteta.
But Leno is glad to see his old side challenging at the top end of the table, and wants them to go all the way.
"I don't have toxic [feelings] or bad energy for Arsenal," the 31-year-old Standard Sport.
"It didn't end in the perfect way, but my reception at the Emirates was really good.
"I get fans coming up to me saying, 'thank you for your four years... you were very good'.
"I was really happy with my performances. Even when they dropped me, I did nothing wrong. I came through the front door and I left through the front door. I still have a connection to the club."
When pressed on Arsenal's bid to hold off a title pursuit by Manchester City, Leno added: "I hope they do it, I think they can."
